This invention is concerned with substituted chromene derivatives of the general formula 
in which
R1 represents alkyl or cycloalkylalkyl,
R2 and R3 each independently represent alkyl or cycloalkyl or taken together with the adjacent carbon atom represent a saturated 3- to 6-membered carbocyclic or heterocyclic ring, the alkyl, cycloalkyl, carbocyclic or heterocyclic ring being unsubstituted or substituted, and
R4 represents hydrogen, halogen, cyano, alkyl, alkylthio, alkenyl, alkynyl, hydroxyalkyl, hydroxyalkynyl, alkoxyalkyl, alkoxyalkynyl, trialkylsilyl, aryl or heteroaryl,
and pharmaceutically acceptable acid addition salts of these compounds.
The above compounds are novel and possess valuable antibiotic properties. They can be used in the control and prevention of infectious diseases. In particular, they exhibit a pronounced antibacterial activity, including against multi-resistant gram-positive strains, such as Streptococcus pneumoniae and Staphylococcus aureus. These compounds can also be administered in combination with known antibacterially active substances and then exhibit a synergistic effect. Typical combination partners are e.g. sulphonamides, which can be admixed with the compounds of formula I or their salts in various ratios.
Objects of the present invention are compounds of formula I and their pharmaceutically acceptable acid addition salts per se and their use as therapeutically active substances; medicaments based on these substances, optionally in combination with sulphonamides, and their production; the use of these substances as medicaments and for the production of antibacterially-active medicaments; as well as the manufacture of the compounds of formula I and their pharmaceutically acceptable acid addition salts and intermediates for their manufacture.
The groups named above are defined below. In combined residues such as hydroxyalkyl, cycloalkylalkyl etc. the exemplification is to be understood accordingly.
The term xe2x80x9chalogenxe2x80x9d means fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine.
The term xe2x80x9calkylxe2x80x9d denotes a straight or branched chain hydrocarbon group which carries up to and including 6, preferably 4 carbon atoms, if not otherwise specified. Examples are, e.g., methyl, ethyl, n-propyl, isopropyl, isobutyl, sec-butyl, t-butyl. The alkyl group being optionally substituted, e.g., by halogen (e.g. chlorine, bromine, fluorine); cyano; lower alkoxy (e.g. methoxy, n-butoxy); nitro; amino; lower alkoxycarbonylamino (e.g. t-butoxycarbonylamino); lower alkanoylamino (e.g. acetylamino).
The term xe2x80x9calkoxyxe2x80x9d and xe2x80x9calkylthioxe2x80x9d denote groups wherein the alkyl part is as defined above and which are attached via an oxygen or sulfur atom, respectively, examples of such groups are methoxy, ethoxy, n-propoxy, isopropoxy, isobutoxy, sec-butoxy, t-butoxy; and methylthio, ethylthio, n-propylthio, isopropylthio, isobutylthio, sec-butylthio, t-butylthio.
xe2x80x9cAlkenylxe2x80x9d and xe2x80x9calkynylxe2x80x9d are unsaturated straight or branched chain hydrocarbon groups which carry up to and including 6, preferably 4 carbon atoms having at least one double or triple bond, respectively, e.g. vinyl, 2-propenyl, 2,4-butadienyl, isopropenyl; 1-propynyl, 2-propynyl, 1-butynyl, 3-butynyl. These groups may be unsubstituted or substituted. Examples of substituted alkynyl groups are, e.g., 3-hydroxy-1-propynyl, 3-hydroxy-1-butynyl, 3-methoxy-1-propynyl.
xe2x80x9cCycloalkylxe2x80x9d denotes a saturated carbocyclic group which carries 3 to 6 carbon atoms, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. The cycloalkyl group being optionally substituted, e.g., by halogen (e.g. chlorine, bromine, fluorine); cyano; lower alkoxy (e.g. methoxy, n-butoxy); nitro; amino; lower alkoxycarbonylamino (e.g. t-butoxycarbonylamino); lower alkanoylamino (e.g. acetylamino).
xe2x80x9cCycloalkylalkylxe2x80x9d denotes the combination of cycloalkyl and alkyl as defined above, e.g., cyclopropylmethyl, 2-cyclopropylethyl, cyclopentylmethyl.
xe2x80x9cCarbocyclic ringsxe2x80x9d (formed with R2 and R3) are saturated and contain 3 to 6 carbon atoms, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. This carbocyclic group being optionally substituted, e.g., by halogen (e.g., chlorine, bromine, fluorine); cyano; lower alkoxy (e.g. methoxy, n-butoxy); nitro; amino; lower alkoxycarbonylamino (e.g. t-butoxycarbonylamino); lower alkanoylamino (e.g. acetylamino).
Heterocyclic rings (formed with R2 and R3) refer to heterocyclic, saturated 3 to 6 membered rings containing one or two heteroatoms selected from nitrogen, oxygen and sulfur, e.g. aziridinyl, oxiranyl, thiiranyl, azetidinyl, oxetanyl, thietanyl, pyrrolidinyl, tetrahydrofuryl, tetrahydrothienyl, piperidyl, tetrahydropyranyl, tetrahydrothiopyranyl, morpholinyl, thiomorpholinyl, piperazinyl, dioxolanyl, imidazolidinyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, pyrazolidinyl, etc. These rings may be further substituted, e.g. by t-butoxycarbonyl.
xe2x80x9cArylxe2x80x9d denotes phenyl or naphthyl groups which can optionally be substituted e.g. by halogen (e.g. chlorine, bromine, fluorine); cyano; lover alkoxy (e.g. methoxy, n-butoxy); nitro; amino; lower alkoxycarbonylamino (e.g. t-butoxycarbonylamino); lower alkanoylamino (e.g. acetylamino).
xe2x80x9cHeteroarylxe2x80x9d denotes 5- or 6-membered heteroaromatic groups which contain one or more rings and which have 5-9 carbon atoms and 1-4 hetero atoms, preferably N, O and/or S. Examples of such rings are for example furyl, pyranyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, oxadiazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl and triazinyl. These groups can also be fused preferably to a phenyl ring, e.g. benzopyranyl, benzofuranyl, indolyl and quinolinyl. The xe2x80x9cheteroaryl groupsxe2x80x9d are unsubstituted or substituted by halogen (e.g. chlorine, bromine, fluorine); cyano; lower alkoxy (e.g. methoxy, n-butoxy); nitro; amino; lower alkoxycarbonylamino (e.g. t-butoxycarbonylamino); lower alkanoylamino (e.g. acetylamino).
Preferred compounds of formula I are:
5-(4-Bromo-8-methoxy-2,2-dimethyl-2H-chromen-6-ylmethyl) -pyrimidine-2,4-diamine,
5-[(4-bromo-2xe2x80x2,3xe2x80x2,5xe2x80x2,6xe2x80x2-tetrahydro-8-methoxyspiro[2H-1-benzopyran-2,4xe2x80x2-[4H]pyran]-6-yl) -methyl]-2,4-pyrimidinediamine,
5-(8-ethoxy-2,2,4-trimethyl-2H-chromen-6-ylmethyl) -pyrimidine-2,4-diamine,
5-(4-chloro-8-methoxy-2,2-dimethyl-2H-chromen-6-ylmethyl)-pyrimidine-2,4-diamine,
5-(8-ethoxy-4-ethyl-2,2-dimethyl-2H-chromen-6-ylmethyl)-pyrimidine-2,4-diamine,
5-(8-methoxy-2,2-dimethyl-4-methylsulfanyl-2H-chromen-6-ylmethyl)-pyrimidine-2,4-diamine,
5-(8-ethoxy-2,2-dimethyl-4-propyl-2H-chromen6-ylmethyl) -pyrimidine-2,4-diamine,
5-[8-methoxy-4-(3-methoxy-prop-1-ynyl)-2,2-dimethyl-2H-chromen-6-ylmethyl]-pyrimidine-2,4-diamine,
5-[4-(4-fluoro-phenyl)-8-methoxy-2,2-dimethyl-2H-chromen-6-ylmethyl]-pyrimidine-2,4-diamine,
5-[(4-bromo-8-ethoxyspiro[2H-1-benzopyran-2,1xe2x80x2-cyclobutan]-6-yl)methyl]-2,4-pyrimidinediamine,
5-(4-bromo-8-ethoxy-2,2-dimethyl-2H-chromen-6-ylmethyl)-pyrimidine-2,4-diamine
and their pharmaceutically acceptable acid addition salts.
The compounds of formula I form pharmaceutically acceptable acid addition salts with organic and inorganic acids. Examples of acid addition salts of compounds of formula I are salts with mineral acids, for example hydrohalic acids such as hydrochloric acid, hydrogen bromide and hydrogen iodide, sulphuric acid, nitric acid, phosphoric acid and the like, salts with organic sulphonic acids, for example with alkyl- and arylsulphonic acids such as methanesulphonic acid, p-toluenesulphonic acid, benzenesulphonic acid and the like as well as salts with organic carboxylic acids, for example with acetic acid, tartaric acid, maleic acid, citric acid, benzoic acid, salicyclic acid, ascorbic acid and the like.
The compounds of formula I and their pharmaceutically acceptable acid addition salts can be manufactured by methods known in the art, especially in accordance with the invention by
a) reacting a compound of the general formula 
xe2x80x83in which R1-R4 have the above significance, X represents a leaving group, and any functional group thereon being optionally protected,
with guanidine and cleaving off any protecting group present, or
b) for the manufacture of compounds of formula I in which R4 is other than hydrogen or halogen reacting a compound of the general formula 
with a compound of the general formula
R40Yxe2x80x83xe2x80x83III
xe2x80x83in which R1-R3 have the above significance, R40 is as R4 except hydrogen and halogen, any functional group in R1-R3 and R40 being optionally protected, one of the symbols X and Y represents a leaving group and the other represents a group which is eliminated with this leaving group,
and cleaving off any protecting group present, or
c) converting a compound of formula I into a pharmaceutically acceptable acid addition salt.
The cyclization of the starting materials of formula II (where the xe2x95x90CHX group can be either in (E)- or (Z)-configuration) with guanidine or a salt thereof in accordance with variant a) of the process in accordance with the invention is preferably carried out in an inert organic solvent, preferably in a lower alkanol, e.g. ethanol, or in dimethyl sulphoxide, tetrahydrofuran or dioxan, and at about 50 to 100xc2x0 C. The guanidine is preferably used as a salt, e.g. as the hydrochloride, in which case the reaction is preferably carried out in the presence of a base, e.g. potassium t-butylate. In formula II the leaving group X is preferably bromine, iodine, methylsulfonyloxy, trifluoromethylsulfonyloxy, phenylsulfonyloxy or p-tolylsulfonyloxy.
In the reaction of the compounds Ia and III in accordance with variant b) of the process in accordance with the invention there are to be understood under eliminating groups leaving groups X and, respectively, Y which react with one another and accordingly both xe2x80x9celiminatexe2x80x9d with the formation of an eliminating byproduct. Many possibilities present themselves to a person skilled in the art in this respect; the following embodiments are mentioned as examples:
X=bromine, iodine, methanesulfonyloxy, trifluoromethanesulfonyloxy, phenylsulfonyloxy, p-tolylsulfonyloxy;
Y=(OH)2Bxe2x80x94.
This reaction with a boronic acid derivative III, also known as a xe2x80x9cSuzuki couplingxe2x80x9d, is preferably effected in an inert organic solvent such as e.g. dioxane, tetrahydrofuran or dimethyl sulfoxide at a temperature between about 20xc2x0 C. and the boiling point of the reaction mixture. A base such as an alkali metal carbonate, e.g. potassium carbonate, is preferably added as well as a catalyst, preferably a palladium complex such as tetrakis-(triphenylphosphine)-palladium.
A metal compound with Y=xe2x80x94Sn(lower-alkyl)3, e.g. xe2x80x94Sn(CH33 or xe2x80x94Sn(n-butyl)3 (xe2x80x9cStille reactionxe2x80x9d); xe2x80x94MgHal (xe2x80x9cGrignard couplingxe2x80x9d); or xe2x80x94ZnHal and Hal=bromine or iodine can be used in the above reaction as the reaction partner III. No base is used in this reaction, although the catalyst described above is preferably used. It can also be advantageous to add an inert salt, especially lithium chloride.
The aforementioned reaction can also be carried out with interchanged substituents X and Y, e.g. with X=xe2x80x94Sn(CH3)3, xe2x80x94MgHal or xe2x80x94ZnHal and Y=bromine, iodine, methanesulfonyloxy, trifluoromethanesulfonyloxy, phenylsulfonyloxy, p-tolylsulfonyloxy. The reaction conditions are essentially the same.
Functional groups, such as amino groups, should be protected. A suitable protecting group for amino is e.g. t-butoxycarbonyl. Such group can be split off (cf. Example 24) hydrolytically with acid treatment, e.g. trifluoroacetic acid, or mineral acid such as hydrochloric acid, in an organic solvent e.g. methylene chloride or chloroform.
The manufacture of the acid addition salts of the compounds of formula I in accordance with variant c) can be effected in a manner known per se, e.g. by reacting a compound of formula I with an equivalent amount of the desired acid, conveniently in a solvent such as water or in an organic solvent such as ethanol, methanol or acetone. The temperature at which the salt formation is carried out is not critical. It generally lies at room temperature, but can also readily be lower or higher, for example in the range of 0xc2x0 C. to +50xc2x0 C.
Compounds of formula I can be prepared by elaborating an aldehyde of formula IV optionally protected, according to known procedures by reacting it first with 3-anilinopropionitrile in the presence of a base, preferably KOtBu, and then heating the intermediate with an excess of guanidine hydrochloride and base, preferably KOtBu, in ethanol. 
a] If R4=aryl or heteroaryl
xe2x80x83the intermediate IV can be synthesized by coupling either free aldehyde IVa or a corresponding acetal V with an aryl- or heteroaryl boronic acid 
xe2x80x83according to typical xe2x80x9cSuzuki-conditionsxe2x80x9d (as in the above variant b) in an inert organic solvent like dimethylformamide, tetrahydrofuran, dioxane or dimethoxyethane at a temperature between 20xc2x0 and the boiling point of the reaction mixture in the presence of a base, preferably K3PO4 or Na2CO3, and a Pd-catalyst, preferably Pd(Ph3P)4.
A convenient variant generates the Suzuki-reagent in situ by reacting an aryl- or heteroaryl bromide or iodide with 4,4,5,5,4xe2x80x2,4xe2x80x2,5xe2x80x2,5xe2x80x2-octamethyl[2,2xe2x80x2]bi[[1,3,2]dioxa-borolanyl] in the presence of a Pd-catalyst, preferably PdCl2(dppf), and KOAc in DMF (Tetrahedron Letters 1997, 3841).
b] If R4=alkynyl
xe2x80x83the intermediate IV can be synthesized by coupling either free aldehyde IVa or a corresponding acetal V with an alkyne according to typical Sonogashira-conditions, i.e. a Pd-catalyst, e.g. (Ph3P)2PdCl2 or Pd(Ph3P)4, a copper salt like CuI, and a base like triethylamine or piperidine, without solvent or in an inert solvent like dimethylformamide.
c] If R4=alkyl, trialkylsilyl, alkylthio, or hydroxyalkyl
xe2x80x83the intermediate IV can be synthesized by subjecting compound V to a metal/halogen-exchange with nBuLi or tBuLi and reacting the resultant derivative VI with an electrophile, i.e. an alkyl halide, tosylate or trifluoromethanesulfonate, a trialkylsilyl halide, a dialkyl disulfide, or an aldehyde or ketone. 
d] If R4=Cl
xe2x80x83the intermediate IV can be synthesized by reacting the above prepared derivative VI with mesyl-Cl as electrophile, yielding, after cleavage of the acetal, the corresponding compound IV with R4=Cl.
Intermediate V is derived from intermediate IVa by treatment with Me3OSiCH2CH2OSiMe3 at xe2x88x9278xc2x0 in CH2Cl2 and trifluoromethanesulphonic acid trimethylsilyl ester as catalyst (Tetrahedron Letters 1980, 1357).
Intermediate IVa is synthesized from intermediate IVb by a bromination-dehydro-bromination-sequence involving treatment with Br2 in CH2Cl2 at xe2x88x9278xc2x0 followed by DBN- or DBU-induced elimination of HBr in an inert solvent like tetrahydrofuran. 
Aldehyde IVb is available by a Heck-type-reaction-ring closure according to literature precedents using iodo-phenol VII and vinyl-alcohol VIII in the presence of a Pd-catalyst like Pd(POAc)2 and a base like NaHCO3 in an inert solvent like dimethylformamide (Tetrahedron Letters 1991, 7739). 
Iodo-phenol VII is available by iodination of IX according to standard conditions (N-iodo-succinimide in acetonitrile); the latter can be prepared by mono-alkylation of 3,4-dihydroxy-benzaldehyde X involving deprotonation with a base, preferably NaH in dimethylformamide, followed by reaction with an alkyl bromide or iodide. 
The illustrative synthetic schemes follow below.

wherein the symbols are as defined above.


The symbols are as defined above.
The above-mentioned procedure can be applied for the cleavage of the aldehyde protecting group of compounds 10-17.




the symbols used in the above schemata are as defined above.
The abbreviations have the meanings given below:
TMS=trimethylsilyl
TMSOTf=trifluoromethanesulphonic acid trimethylsilyl ester
DBN=1,5-diazabicyclo[4.3.0]non-5-ene
DBU=1,8-diazabicyclo[5.4.0]undec-7-ene
TPP=triphenylphosphin(yl)
DMF=dimethylformamide
Bu=butyl
R5-R9=alkyl
R10=alkyl, hydroxyalkyl, alkoxyalkyl, trialkylsilyloxyalkyl
DMSO=dimethylsulfoxide
Ph=phenyl
EtOH=ethanol
As mentioned earlier, the compounds of formula I and their pharmaceutically acceptable salts possess valuable antibacterial properties. They are active against a large number of pathogenic microorganisms such as e.g. Staphylococcus areus, Streptococcus pneumoniae etc. by virtue of their action in inhibiting bacterial dihydrofolate reductase (DHFR).
The inhibition of the enzyme was taken as a measurement for the antibacterial activity. It is determined using the method of Baccanari and Joyner (Biochemistry 20, 1710 (1981)); see also P. G. Hartman et al., FEB 242,157-160 (1988).
The IC50 values (concentration at which the enzyme is inhibited to 50%) are determined graphically.
The following Table contains inhibitory concentrations determined in the above test for representative members of the class of compound defined by formula I. The following microorganisms were tested:
Col. 1: MIC Spn1/1; xcexcg/ml (Streptococcus pneumoniae 1/1, Trimethoprim- and Penicillin-resistant, Serotype 6; clinical isolate, stored at xe2x88x9280xc2x0 C.)
xe2x80x83Lit.: H. Locher et al., Can. J. Infect. Dis.6: Suppl. C, p 469C.
Col. 2: MIC Sa101; xcexcg/ml (Staphylococcus aureus 101, MRSA*)xe2x80x94 and Trimethoprim-resistant; clinical isolate, stored at xe2x88x9280xc2x0 C.)
xe2x80x83Lit.: A. Burdeska et al., FEBS 266:159-162, 1999; G. Dale et al., J. Mol. Biol. 266:23-30, 1997.
Col. 3: DHFR Spn1/1; xcexcMxe2x80x94the IC50-values in xcexcM against the purified DHFR of the above strain Sp1/1 of Streptococcus pneumoniae. 
Col. 4: DHFR Sa1; xcexcMxe2x80x94the IC50-values in xcexcM against the purified DHFR of the strain 157/4696 (highly trimethoprim-resistant; clinical isolate) of Staphylococcus aureus 
xe2x80x83Lit.: A. Burdeska et al., FEBS 266:159-162, 1999; G. Dale et al., J. Mol. Biol. 266:23-30, 1997.
*) MRSA=Methicillin Resistant Staphylococcus Aureus 
The products in accordance with the invention can be used as medicaments, e.g. in the form of pharmaceutical preparations for enteral or parenteral administration. The products in accordance with the invention can be administered, for example, perorally, e.g. in the form of tablets, coated tablets, dragxc3xa9es, hard and soft gelatine capsules, solutions, emulsions or suspensions, rectally, e.g. in the form of suppositories, or parenterally, e.g. in the form of injection solutions. The invention thus also relates to a method of prophylaxis and treatment of infectious diseases which comprises administering a compound of formula I alone or in combination with a sulphonamide.
The production of the pharmaceutical preparations can be effected in a manner which will be familiar to any person skilled in the art by bringing the substances in accordance with the invention, if desired in combination with other therapeutically valuable substances, into a galenical administration form together with suitable, non-toxic, inert, therapeutically compatible solid or liquid carrier materials and, if desired, the usual pharmaceutical adjuvants.
Not only inorganic carrier materials, but also organic carrier materials are suitable as such carrier materials. Thus, lactose, corn starch or derivatives thereof, talc, stearic acid or its salts can be used, for example, as carrier materials for tablets, coated tablets, dragxc3xa9es and hard gelatine capsules. Suitable carriers for soft gelatine capsules are, for example, vegetable oils, waxes, fats and semi-solid and liquid polyols (depending on the nature of the active substance no carriers are, however, required in the case of soft gelatine capsules). Suitable carrier materials for the production of solutions and syrups are, for example, water, polyols, sucrose, invert sugar and glucose. Suitable carrier materials for injection solutions are, for example, water, alcohols, polyols, glycerol and vegetable oils. Suitable carrier materials for suppositories are, for example, natural or hardened oils, waxes, fats and semi-liquid or liquid polyols.
The usual preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, flavorants, salts for varying the osmotic pressure, buffers, coating agents and antioxidants come into consideration as pharmaceutical adjuvants.
For parenteral administration the compounds of formula I and, respectively their salts are preferably provided as lyophilizates or dry powders for dilution with conventional carriers such as water or isotonic saline.
As already mentioned, the compounds of formula I and their salts have antibacterial activity. They inhibit bacterial dihydrofolate reductase and potentiate the antibacterial activity of sulphonamides such as e.g. sulfisoxazole, sulfadimethoxine, sulfamethoxazole, 4-sulphanilamido-5,6-dimethoxy-pyrimidine, 2-sulphanilamido-4,5-dimethyl-pyrimidine or sulfaquinoxaline, sulfadiazine, sulfamonomethoxine, 2-sulphanilamido-4,5-dimethyl-isoxazole and other inhibitors of enzymes which are involved in folic acid biosynthesis, such as e.g. pteridine derivatives.
Oral, rectal and parenteral administration come into consideration for the treatment of hosts, especially warm-blooded hosts, e.g., in human medicine, with the compounds of formula I or combinations thereof with sulphonamides. A daily dosage of about 0.2 g to about 2 g of a compound of formula I in accordance with the invention comes into consideration for adults. When administered in combination with antibacterial sulphonamides the ratio of compound I to sulphonamide can vary within a wide range; it amounts to e.g. between 1:40 (parts by weight) and 1:1 (parts by weight); 1:10 to 1:2 are preferred ratios. Thus, e.g. a tablet can contain 80 mg of a compound I in accordance with the invention and 400 mg of sulfamethoxazole, a tablet for children can contain 20 mg of a compound I in accordance with the invention and 100 mg of sulfamethoxazole; syrup (per 5 ml) can contain 40 mg of compound I and 200 mg of sulfamethoxazole.
The compounds of formula I are characterized by a high antibacterial activity and, respectively, a pronounced synergistic effect in combination with sulphonamides and good tolerance.
The following Examples illustrate the invention. The temperatures are given in degrees Celsius.